Estimate of carbonate production by scleractinian corals at Luhuitou fringing reef, Sanya, China

Abstract

Carbonate production by scleractinian corals not only maintains coral reef growth, but also represents an important source of atmospheric carbon dioxide. In this paper the carbonate production by scleractinian corals at Luhuitou fringing reef, Sanya, Hainan Island, China, is investigated with an ecological census-based method. Averaged carbonate production is 1.16 +/- 0.55 kg center dot m(-2) center dot a(-1) and 3.52 +/- 1.32 kg center dot m(-2) center dot a(-1) on the reef flat and reef slope, respectively, depending on the composition and distribution of corals and the intergeneric difference of skeletal growth. In response to the rapidly increasing human impacts, coral carbonate production has decreased by 80%-89% at this fringing reef since the 1960s; as a result, the reef accretion rate declined and became lower than the rate of sea level rise. Further development of the Luhuitou fringing reef will switch significantly from lateral extension seawards to vertical growth, reflecting a response of coral reef bio-geomorphic process to strong human impacts under the background of global sea level rise. In addition, decrease in coral carbonate production reduced CO2 release from this fringing reef. In the future, it is likely that the role played by coral reefs, especially of fringing reefs, in the ocean and even in the global carbon cycle will be modified or weakened by the increasing human impacts.